Spatial working memory in Wistar rats: brain sex differences in metabolic activity

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Cognitive Neuroscience

Background:

• Sex differences in spatial learning abilities are well-documented.
• Spatial working memory (WM) is crucial for navigation and learning.
• Understanding sex-specific neural mechanisms underlying WM is important.

Purpose of the Study:

• To investigate sex-dependent differences in the neural substrates of spatial working memory acquisition.
• To compare the oxidative metabolic activity in specific brain regions between male and female rats after a spatial WM task.

Main Methods:

• Utilized the Morris water maze to assess spatial WM acquisition in adult male and female Wistar rats.
• Employed cytochrome oxidase (COx) histochemistry to measure oxidative metabolic activity in limbic system regions.
• Included control groups (free swimming and untrained) to differentiate learning-specific changes.

Main Results:

• Both sexes exhibited similar spatial performance, with males requiring slightly more trials to significantly reduce escape latencies.
• Males showed decreased COx activity in the medial prefrontal cortex, lateral septum, and dentate gyrus compared to controls.
• Females displayed increased COx activity in the nucleus accumbens, ventral tegmental area, and supramammillary region compared to controls.

Conclusions:

• Spatial WM acquisition involves distinct neural subsystems in a sex-dependent manner.
• The hippocampus appears central for spatial WM in males.
• Other brain structures, including the nucleus accumbens and ventral tegmental area, may be more central for spatial WM in females.